Note: Descriptions are shown in the official language in which they were submitted.
CA 02530260 2007-09-24
EXPANSION-DEFLECTION COUPLING
FIELD OF THE INVENTION:
100021 The present invention relates generally to a coupling used to couple
electrical
conduits. More particularly, the present invention relates to an expansion-
deflection joint
coupling which is flexible in axial expansion and compression and angular
deflection while
providing protection to the electrical wires it contains.
BACKGROUND OF THE INVENTION:
[0003] Electrical conduit is typically used to support runs of electrical
wires or cables.
These conduits in certain instances are required to be grounded and may be
subject to
movement relative to each other. Such relative movement requires the use of
expansion-
deflection type couplings to prevent damage to the conduit or the cables
inside. Conduits
supporting such electrical wires or cables may be interconnected by electrical
fitting joints.
Certain of these joints provide for thermal expansion, permitting relative
movement between
the conduits in response to ambient temperature fluctuations. These joints
must not only
provide for relative movement between the conduits, but also must maintain
ground continuity
across the conduits during such movement. Expansion-deflection type couplings
are also
necessary to
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577-699 (T&81831) PATENT
provide the flexibility to accommodate such movement. Thus, expansion-
deflection type
couplings will allow for expansion, contraction and deflection caused by the
relative movements
as discussed above.
[0004] Examples of such expansion-deflection type couplings are shown in U.S.
Patent
No. 2,885,461; 3,783,431 and 4,109,097,
[0005] U.S. Patent No. 2,885,461 shows an expansion and deflection conduit
coupling
made of two end sleeves yieldingly connected in spaced apart end to end
relation by a
surrounding flexible elastic sleeve or tube made of plastic. Such a coupling
will allow for
expansion, contraction and deflection of the conduit without damaging the
conduit and providing
the necessazy electric eontinuity,
[0006] U.S. Patent No. 3,783,431 shows an electrie connector with a tubular
contact
meniber having two universal joints mounting on the contact members to permit
angular
niovement of the contact members relative to each other. A longitudinal
movement of the
contact member is caused by sliding a rod contact within the tubular contact.
Furthermore, a
tubular sheath of flexible material encircles a portion of the rod contact
outside the tubular
contact to weaken any ice forming thereabout to maintain the free movement
inside the
connector.
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[0007] U.S. Patent No. 4,109,097 shows an expansion-deflection coupling
comprised of
two independent hubs adapted to be threaded on the ends of opposed spaced
apart conduits, a
flexible grounding strap is connected completely within and between the hubs
and a flexible
watertight jacket is secured to the outer surface of the hub. Such a coupling
allows for linear
misalignment of the hubs up to 3/4 of an inch and/or angular displacement of
the hubs relative
to each other up to 30 and also allows for expansion or contraction of the
coupling up to 3/4 of
an inch.
[0008] The expansion-deflection couplings as discussed above in the prior art
use an
internal plastic sleeve to maintain constant inner diameter in any position
and provide a smooth
wire way for protection of wire insulation. Such couplings have very limited
flexibility in
expansion or contraction, in angular deflection and further in line or
misalignment.
[0009] It is desirable therefore to provide an expansion-deflection coupling
which will
have more flexibility in axial expansion, and compression and angular
deflection while
providing protection to the wires or cables it contains.
SUMMARY OF THE INVENTION:
[0010] The present invention discloses an expansion-deflection coupling having
a pair
of hub fittings positioned at opposing ends of the coupling. Each hub fitting
has an internal
diameter compatible with an external diameter of an electrical conduit
coupling for attachment
thereto. The coupling also includes a flexible hollow cylinder extending
between the hub
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fittings defining a space within. Also included is at least one mid-coupling
located within the
cylinder, and at least two funneled tubes extending within the cylinder,
wherein each of the
funneled tubes includes opposed flared ends. At least two of the flared ends
are movably
secured to the at least one mid-coupling and one flared end is movably secured
to each of the
hub fittings.
BRIEF DESCRIPTION OF THE DRAWINGS:
[0011] Figure 1A is a longitudinal sectional view of a coupling according to
one
embodiment of the present invention.
[0012] Figure 1B is a cross sectional view along the line 2-2 of Figure 1A.
[0013] Figure 2A is a longitudinal sectional view of the coupling according to
an
alternate embodiment of the present invention.
[0014] Figure 2B is a cross sectional view along the line 3-3 of Figure 2A.
[0015] Figure 3 is a longitudinal partial view of the inside and the outside
portion of the
coupling according to the present invention.
[0016] Figure 4 is a longitudinal view of the outside portion of the coupling
according
to the present invention.
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577-699 (T&B 1831) PATENT
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017) The expansion-deflection coupling according to the present invention
may be used
with rigid metal conduit and 1.?~IC, to couple together two sections of
conduit subject to
movement relative to each other. The cxpansion joints are installed without
the need for unit
disassembly. The expansion joints are internally grounded and, therefore, do
not require an
external bonding jumper when used indoor or outdoor. The expansion joints of
the present
invention may be used with long conduit runs to permit linear movement caused
by thennal
expansion and contraction. Also, for long conduit runs the expansion joints
prevent conduits
from buckling and possible resulting circuit failures. The expansion joints of
the present
invention meet the requirements of the National Electrical Code, providing an
electrically
continuous raceway with no additional bonding means required.
[0018] Furthermore, the coupling of the present invention provides greater
flexibility in
axial expansion and compression, angular deflection and parallel offset
movements without
collapsing or fracturing, and damaging the electrical wires it contains, as
will be described in
greater detail below. The coupling of the present invention can be
manufactured at reasonable
cost in a variety of sizes adapted to be compatible with standard conduits of
differing diameters.
The coupling will be smaller and lighter in design and can be assembled in
virtually any lengths.
Additionally, the coupling can be readily installed and will be durable and
long lasting, suitable
for use in various environments.
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[0019] Referring now to Figures 1 A and 1 B as shown in Figure 1, there is
shown an
expansion-deflection coupling (hereinafter "coupling") 10 of the present
invention. The
coupling 10 includes a pair of hubs 11 and 12 which are similar to each other.
The hub 11 is
positioned at one end of the coupling 10 while hub 12 is positioned at the
opposing end. The
hub 12 preferably has an internal diameter compatible with an external
diameter of a union
coupling 13, preferably an expansion coupling, to accommodate a conduit (not
shown) to which
it is secured. The hub 12 is secured to the union coupling 13 via a union nut
14 as shown.
[0020] A flexible extruded hollow cylinder 15 preferably made of rubber
extends from
hub 11 to hub 12. The cylinder 15 defines an internal chamber between the hubs
11 and 12.
The cylinder 15 is preferably clamped to the ends of the outer surface of each
of the hubs 11
and 12 by means of conventional clamps 16. The compressive force exerted by
the clamps 16
will provide a waterproof connection between the cylinder 15 and the hubs 11
and 12. The
clamps 16 are preferably made of stainless steel material.
[0021] In the preferred embodiment, the coupling 10 further includes at least
one
circular mid-coupling 17 preferably made of cast iron, "floating" inside the
cylinder 15. At
least two funneled tubes 18, are assembled inside the hollow cylinder 15 as
shown in Figure
1 A. The tubes 18 are preferably made of steel, however, they can be made of
plastic. Each of
the funneled tubes 18 includes a central cylindrical tubular configuration 18a
having a central
interior bore 18b defining a hollow cylindrical aperture for receipt therein
of the electrical
wires, cables
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577-699 (T&B 1831) PATENT
or the like. The funneled tube 18 also include opposed flared ends 18c and 18d
defining a
substantially circular opening. The funneled tubes 18 will prevent wires
getting caught up by
creating more space for the wires to run through. The funneled tubes 18 will
also reduce friction
diu-ing wire pull through to provide greater wire protection and easier wire
pulling.
[0022] The hubs l land 12 and the mid-coupling 17 cover each end 18c and 18d
of the
funneled tubes 18 as shown in Figure 1A. One end 18c of tubel8 is preferably
snapped to the
hubs 11 and 12, while the other end 18d is snapped to the mid-coupling 17.
Specifically, each of
the hubs 11 and 12 include inwardly projecting lips 11 a and 12a respectively,
to effectively hold
the fimneled tubes 18 by snapping into place onto the end 18c of the funneled
tube 18. Similarly,
interior mid-coupling 17 also includes projecting lips 17a to effectively hold
the funneled tubes
18 by snapping into place onto the end 18d of the funneled tube 18, Thus,
funneled tube 18
operates much like a"balP' to the corresponding "socket" in mid-coupling 17 or
hub 11 or 12.
[0023} A flexible braid 19 is secured by braid screws 20 on top of each of the
hubs 11
and 12. As shown in Figure 1A, the braid 19 extends longitudinally from one
end of the hub 11
to the other end of the hub 12. Since the braid 19 and the screws 20 are
positioned within the
cylinder 15, the braid and the screws are completely protected from any damage
which might
occur from wrenching, corrosion, or otherwise.
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577-699 (T&B 1831) PATENT
[0024] The length of the coupling 10 may preferably be varied as shown in
Figure 2A and
Figure 2B. This embodiment of the invention employs two mid-couplings 17 and
three funneled
tubes 18 as shown. The funneled tubes 18 are connected in a similar manner as
described above,
However, in this case, the projecting lips 17a of the mid-coupling 17 snaps
into place onto both
ends 18c and l8d of the additional third funneled tube 18 as shown. Even
though the mid-
couplings 17 that are "floating' inside will move somewhat they will not
execute excessive
movement due to at least one end of funneled tube 18 being snappcd into each
of these mid-
couplings 17. Additionally, each of these funneled tubes 18 will be able to
expand or contract in
any direction within the hollow cylinder 15.
[0025] The coupling assembly of the present invention is much smaller and
lighter in
design and can be assembled in virtually any length, preferably in 4"
increments employing
additional mid-couplings 17 and tubes 18. The flexible hollow cylinder 15 can
be cut to a
desired length with a specific number of funnel tubes 18 and mid-couplings 17
as shown in
Figure 3. As discussed above, each end will have a hub 11 and 12 respectively
with the one end
of the coupling fitted to accommodate a conduit (not shown).
[0026] Figure 4 show a longitudinal view of the outside portion of the
coupling 10
according to the present invention. As discussed above, hollow cylinder 15 is
preferably made of
rubber. Consequently, due to the flexibility of the hollow cylinder 15, the
coupling 10 of the
present invention can not only stretch longitudinally, but can flex in any
direction. In fact, with
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the coupling 10 having funneled tubes 18 of up to three or more, as shown in
Figure 2A the
coupling can take an "S" shape if so desired due to mid-coupling 17, hubs 11
and 12, and
funneled tubes 18 operating much like a ball and socket joint.
[0027] The expansion-deflection coupling 10 of the present embodiment allows
for
axial expansion and contraction of up to 1'/z to 2 inches and more. Axial
expansion or
contraction means the axial movement of the hubs is away from or toward each
other. The
angular misalignment of the axes of coupled conduit runs in any direction up
to 45 degrees to
75 degrees and higher, thereby providing a much greater angular displacement
of the hubs
relative to each other. Additionally, the parallel misalignment of the axes of
coupled conduit,
i.e., linear misalignment of the hubs runs in any direction up to 1%2 to 2
inches. The increase in
number of tubes provides for a greater axial expansion and greater angular
displacement of the
hubs relative to each other.
[0028] While the particular embodiments of the present invention have been
shown and
described, it will be obvious to those skilled in the art that changes and
modifications may be
made without departing from the teachings of the invention. The matter set
forth in the
foregoing description and accompanying drawings is offered by way of
illustration only and not
as a limitation.
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